There has been provided an image processing device capable of executing a job including processing of image data, such as scanning, PC printing, facsimile transmission, and the like, and also capable of switching control modes of a control unit. For example, Japanese Patent-Application Publication No. H8-101609 discloses an image processing device including a main controller having a higher-speed CPU and a sub-controller having a lower-speed CPU. Normally, the main controller controls a printer unit and the like, and the sub-controller controls an interface to an external device. In a power-saving mode, however, the main controller is put into a halt state, and only the sub-controller is maintained in an active state, thereby saving power consumption.
It has been considered to switch between a plurality of different control modes when executing jobs so as to improve efficiency. In general, more jobs are expected to be executed at a higher speed in a higher control mode having a higher performance capacity. Thus, in a condition where a large number of jobs are received in a short period of time, efficiency can be enhanced by selecting the higher control mode.